The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.

Winter worm and summer grass (WWSG) is one of the most valued traditional Chinese medicines for fighting cancer, increasing longevity, and improving immunity. It consists of the entomopathogenic fungus Cordyceps sinensis and its natural lepidopteran host Hepialus armoricanus. Using the water extract of Cordyceps militaris, a sibling species of C. sinensis cultivated on an artificial host the silkworm Bombyx mori pupae, we have found that the C. militaris extract inhibited growth of MCF-7 human breast cancer cells in a dose- and time-dependent manner. The inhibitory effect of the C. militaris extract on MCF-7 cells was via an apoptosis cascade by inducing the expression of pro-apoptotic genes and by suppressing anti-apoptotic marker genes. Moreover, the C. militaris extract also inhibits DNA methyltransferase transcription, suggesting that the reduced cancer suppressor gene methylation might lead to the recovery of tumor-suppressor gene expression and eventually to the inhibition of tumor cell growth.